Liquid crystal displays (LCD) are one of the fastest-developed flat panel displays due to having light and thin characteristics. However, thin film transistor LCDs (TFT-LCDs) have a relatively narrow viewing angle in comparison to cathode ray tube (CRT) displays. This drawback prevents its utilization in upmarket display fields which require broad viewing angles, like aviation and medical fields, etc.
Products, whose viewing angles can reach 85 or more degrees horizontally and vertically, have appeared recently with the development of viewing angle technology in LCDs. The viewing angle technologies applied to LCDs include multi-domain vertical alignment (MVA) and in plane switching (IPS). One advantage of MVA is the high contrast ratio which can reach 4000:1 and above; IPS makes the liquid crystals be switched through the electrical field by repeatedly arranging pixel electrodes and common electrodes in parallel. Therefore, wide viewing angles are achieved, but the contrast ratio is generally below 2000:1, which is relatively low.
Major solutions to increase the viewing angle involve making brightness of main pixel units and sub-pixel units different. As shown in FIG. 1, each pixel units of present liquid crystal display panels include a main pixel area and a sub-pixel area. The main pixel area includes a first thin film transistor T1, a first storage capacitor Cst1, a first liquid crystal capacitor Clc1, a first capacitor C1, and a second capacitor C2. The sub-pixel area includes a second thin film transistor T2, a third thin film transistor T3, a second storage capacitor Cst2, and a second liquid crystal capacitor Clc2. The gate of the first thin film transistor T1 and the gate of the second thin film transistor T2 are both connected to a scan line Gn. The source of the first thin film transistor T1 and the source of the second thin film transistor T2 are connected to a data line Data. One side of both the first storage capacitor Cst1 and the first liquid crystal capacitor Clc1 are connected to a drain of the first thin film transistor T1. The other side of the first storage capacitor Cst1 is connected to a common electrode disposed on the side of the array substrate. The other side of the first liquid crystal capacitor Clc1 is connected to a common electrode disposed on the side of the color film substrate. One side of the first capacitor C1 is connected to the drain of the first thin film transistor T1, the other side of the first capacitor C1 is connected to the second capacitor C2. The other side of the second capacitor C2 is connected to a common electrode of the array substrate.
One side of both the second storage capacitor Cst2 and the second liquid crystal capacitor Clc2 are connected to a drain of the second thin film transistor T2. The other side of the second storage Cst2 is connected to a common electrode of the array substrate; the other side of the second liquid crystal Clc2 is connected to a common electrode of the color film substrate. The drain of the second thin film transistor T2 is connected the source of the third thin film transistor T3. The drain of the third thin film transistor T3 is connected to a node between the first capacitor and the second capacitor. The gate of the third thin film transistor T3 is connected to scan line Gn+1.
As shown in FIG. 2, Va and Vb represent the voltage of a main pixel region and a sub-pixel region respectively. During t1-t2, the signal of the scan line Gn is high, T1 and T2 are closed, T3 is opened, Va and Vb are both at high potential. At the time t2, the scan line Gn is closed, the scan line Gn+1 is opened, T1 and T2 are opened, T3 is closed, the second liquid crystal capacitor Clc2 discharges in order to charge the lower-substrate of the first capacitor C1, the voltage of Va is increased, i.e., Va is higher than Vb, so that the viewing angle is increased. However aperture ratio and the transmittance ratio will decrease since the number of the thin film transistors is higher.
Therefore, a liquid crystal display panel and apparatus is required to solve the problems of present technology.